The invention relates to a lamellar or fan-type end grinding wheel in which abrasive or grinding flaps overlapping one another in tile-like manner and which are fixed are located along the circumferential zone of a circular disc-shaped, flexible base or back plate and project through radial slots in the circumferential zone.
Lamellar end grinding wheels can be used in numerous different ways, but are preferably employed in angle grinders. However, such lamellar end grinding wheels can also be used in drilling machines or similar grinding equipment.
A preferred field of use for lamellar end grinding wheels is the smoothing and cleaning of welding seams and spots. In this connection, such lamellar end grinding wheels can also be used for roughing and polishing, without it being necessary to use different wheels or grain sizes. Thus, with the aid of a single tool, it is possible to obtain a particularly good surface quality. However, lamellar end grinding wheels of the present type are also suitable for other operations such as deburring, bevelling, rust removal or removing old paint. It is possible to work the most varied materials such as steel, refined steel, nonferrous metals, aluminium, rigid plastics, artificial stone, rocks, wood or fillers.
In the known lamellar end grinding wheels, the back plate is made from a synthetic material or plastic. However, in the past, the latter has been replaced by vulcanized fibre - pressboard as the back plate material. The abrasive flaps are inserted in the back plate either in recesses provided for this purpose and bonded with synthetic resin, or the abrasive flaps are bonded onto the plastic material of the back plate. It must be ensured that on applying the abrasive flaps to the plastic material of the back plate, said flaps are brought into the arrangement necessary for the abrasive or grinding action, in which the flaps overlap one another in tile-like or flake-like manner.
Although good working results are achieved with the known lamellar end grinding wheels, disadvantages have also been revealed in practice. For example it has been found that in the case of corresponding loading, the plastic back plates can break apart. It has also hitherto been impossible to exclude, even in the case of careful processing, that individual abrasive flaps will be ejected from their fixture during the abrasion or grinding process.
The necessary elasticity of the plastic back plate is generally obtained only as a result of the incorporation of a certain amount of moisture. It was therefore necessary, after the manufacture of the plastic back plate to store it for several weeks under enviromental conditions, so as to permit the necessary moisture absorption. However, due to differing climatic conditions, the storage process was very difficult to calculate, so that wheels were obtained with a not sufficiently defined elasticity. It could also arise that, as a result of the stresses occurring at high speeds or higher working loads, a plastic back plate was broken, which led to a considerable risk of injury.
Difficulties also arose in bonding the synthetic resin used for bonding the abrasive flaps in the plastic back plate. It was found that during operation and with corresponding working loading, there can be such a significant degree of heating that the adhesive became soft, so that individual flaps or groups thereof could be ejected, which also led to a certain risk of injury.
A lamellar end grinding wheel of the aforementioned type is known from U.S. Pat. No. 3,616,581.